Age-dependent tolerance to an endogenous tumor-associated antigen

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Immunologic tolerance to endogenous antigens can suppress anti-tumor immune responses.
• Gp70 is an endogenous tumor-associated antigen (TAA) found in BALB/c-derived colon carcinoma CT26.
• Gp70 mRNA expression is detectable in mouse tissues from 8 months of age.

Purpose of the Study:

• To investigate the role of gp70 in establishing immunologic tolerance.
• To determine the impact of gp70 expression on anti-tumor immunity in an age-dependent manner.
• To explore the relationship between gp70, T-cell responses, and tumor growth control.

Main Methods:

• Utilized gp70-deficient mice and gp70-sufficient mice for comparative studies.
• Assessed tumor growth and control in different mouse models.
• Quantified gp70-specific cytotoxic T-lymphocyte (CTL) responses and antigen-specific T-cell avidity after vaccination.

Main Results:

• Tumor growth was observed in all gp70-sufficient mice.
• Approximately 50% of gp70-deficient mice controlled tumor growth via endogenous T-cell responses.
• Protection in gp70-deficient mice correlated with enhanced gp70-specific CTL responses and increased T-cell numbers and avidity.

Conclusions:

• Age-dependent expression of endogenous TAAs like gp70 contributes to immune tolerance.
• Reduced immunosurveillance with aging may be linked to increased or de novo peripheral TAA expression.
• Targeting endogenous TAAs could be a strategy to enhance anti-tumor immunity.